Tempering is an important step in the production of oily compositions such as chocolate, nut paste, margarine and the like. Tempering is effected so that a solidified product can be readily released from a mold due to formation of fine crystal nuclei when solidifying. Thereby, a product having good properties such as excellent gloss, luster, mouth feel and the like can be obtained (see, for example, Japanese Patent Kokai No. 61-40750).
However, in general, a tempering operation is troublesome and there is a tendency to omit a tempering operation. For this purpose, there has been used a hard butter having a high elaidin content, a hard butter wherein the fatty acid arrangement is randomized by interesterification, or a lauric hard butter. However, miscibility of these hard butters with cacao butter is limited and, thereby, taste and flavor of a resulting product are also limited.
Further, regarding a method for tempering, there are optimum conditions for each production depending upon the particular kind of a hard butter used, its composition and oil content as well as the presence of milk solid but it is not always easy to find out the suitable conditions. Furthermore, almost all refrigerators used for tempering have relatively little versatility, and are assembled so that they are adapted to a specific cooling rate. Accordingly, the degree of tempering of chocolate should be adjusted based on a particular type of a refrigerator to be used, and it is often experienced that a particular tempering style should be preliminarily found out (M. G. Reade, The Manufacture Confectioner/January 1985).
Thus, there have been employed various methods for tempering. However, in general, tempering usually involves at least one step for force-cooling a molten oily composition and at least one step for reheating it (see, for example, "Seika Jiten" page 459, October, 1981, published by Asakura Shoten). It is clear that the loss of energy becomes generally greater, when both cooling and subsequent heating are effected in a single apparatus. Therefore, it is necessary to install two kinds of apparatuses for cooling and heating (Japanese Patent Kokai No. 61-40750). If tempering could be effected only by cooling, the process would be very advantageous from the view point of decreasing the number of process steps as well as with respect to energy and apparatuses. Further, if the tempering manner can be standardized regardless of the kind of chocolate or refrigerator, the range necessary to conduct a preliminary study in a particular tempering style can be limited and this is very convenient from the practical view point.